EP1503073B1 - Unit injector - Google Patents

Unit injector Download PDF

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Publication number
EP1503073B1
EP1503073B1 EP04017275A EP04017275A EP1503073B1 EP 1503073 B1 EP1503073 B1 EP 1503073B1 EP 04017275 A EP04017275 A EP 04017275A EP 04017275 A EP04017275 A EP 04017275A EP 1503073 B1 EP1503073 B1 EP 1503073B1
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EP
European Patent Office
Prior art keywords
pump
inlet channel
pressure
valve
throttle element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Not-in-force
Application number
EP04017275A
Other languages
German (de)
French (fr)
Other versions
EP1503073A1 (en
Inventor
Ralf Marohn
Peter Dr. Voigt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Continental Automotive GmbH
Original Assignee
Siemens AG
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Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP1503073A1 publication Critical patent/EP1503073A1/en
Application granted granted Critical
Publication of EP1503073B1 publication Critical patent/EP1503073B1/en
Not-in-force legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/20—Varying fuel delivery in quantity or timing
    • F02M59/36—Varying fuel delivery in quantity or timing by variably-timed valves controlling fuel passages to pumping elements or overflow passages
    • F02M59/366—Valves being actuated electrically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/001—Pumps with means for preventing erosion on fuel discharge
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/04—Means for damping vibrations or pressure fluctuations in injection pump inlets or outlets
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M57/00—Fuel-injectors combined or associated with other devices
    • F02M57/02—Injectors structurally combined with fuel-injection pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M57/00—Fuel-injectors combined or associated with other devices
    • F02M57/02—Injectors structurally combined with fuel-injection pumps
    • F02M57/022—Injectors structurally combined with fuel-injection pumps characterised by the pump drive
    • F02M57/023—Injectors structurally combined with fuel-injection pumps characterised by the pump drive mechanical
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/04—Fuel-injection apparatus having means for avoiding effect of cavitation, e.g. erosion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/31—Fuel-injection apparatus having hydraulic pressure fluctuations damping elements
    • F02M2200/315—Fuel-injection apparatus having hydraulic pressure fluctuations damping elements for damping fuel pressure fluctuations
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/0012—Valves
    • F02M63/0014—Valves characterised by the valve actuating means
    • F02M63/0015—Valves characterised by the valve actuating means electrical, e.g. using solenoid
    • F02M63/0026—Valves characterised by the valve actuating means electrical, e.g. using solenoid using piezoelectric or magnetostrictive actuators

Definitions

  • the invention relates to a pump-nozzle device with a pump, a valve and a nozzle unit.
  • Such pump-nozzle devices are used in particular for supplying fuel into a combustion chamber of a direct-injection internal combustion engine, in particular a diesel internal combustion engine.
  • the pump, a control unit which also includes an actuator in addition to the valve, which is preferably formed from a piezo stack, and the nozzle unit form a structural unit.
  • the drive of a piston of the pump is preferably via a camshaft of an internal combustion engine by means of a rocker arm.
  • the pump can be hydraulically coupled via the valve to a low-pressure fuel supply device. It is hydraulically coupled on the output side with the nozzle unit. Start of injection and injection quantity are determined by the valve and its actuator.
  • a pump-nozzle device comprising a pump and a valve having a valve member which controls the hydraulic coupling of a spill space to a drain passage.
  • the drainage channel is hydraulically coupled to the pump and a nozzle unit.
  • An inlet channel is provided which is hydraulically coupled to the Abberichtraum.
  • the valve member is associated with a piezoelectric actuator, via which the valve member between two end positions can be adjusted. In a first end position of the valve member of the flow channel is hydraulically coupled to a Ab tenuraum and this in turn with the inlet channel. In a second end position of the valve member of the flow channel is hydraulically decoupled from the Ab tenuraum.
  • the end of injection is determined by controlling the valve member to its first end position by means of the actuator and thus allowing fluid to flow back into the discharge chamber and the inlet channel via the discharge channel, with the result that the pressure in the pump and thus also in the nozzle unit decreases, which in turn leads to a closing of the nozzle unit.
  • Ab tenuvorgang high noise emissions are generated. Such noise emissions are perceived as unpleasant by the driver of a motor vehicle, in which the pump-nozzle device can be installed and must be largely avoided on the one hand in terms of the highest possible ride comfort and on the other due to increasingly stringent statutory provisions regarding noise emissions from vehicles ,
  • the US 2002/0113140 A1 discloses a pump-nozzle device with a piezoelectric actuated control valve via a hydraulic translator, which is used to control a pre-injection is formed with a throttle portion. Through the throttle section, a control of a valve member of the control valve can be made less accurate, while still a pre-injection can be controlled reliably.
  • the object of the invention is to provide a pump-nozzle device which ensures low noise emissions during operation.
  • the invention is based on the recognition that the noise emissions caused during the operation of the prior art pump-nozzle device are essentially caused by cavitation after establishing the hydraulic coupling between the high-pressure fluid drainage channel and the discharge chamber and the drain channel.
  • the resulting Abêtimpuls leads to high-amplitude pressure waves in the fluid in the region of the Abêtraums and the feed channel, which are transmitted in the form of sound waves from the pump-nozzle device to the outside.
  • the invention is characterized in that a throttle element is provided in the inlet channel.
  • the throttle element causes a rapid increase in pressure in the Abberichtraum and slows the outflow of fluid into the inlet channel. This greatly reduces the amount of time that cavitation occurs, thereby greatly attenuating the generation of sound emissions in a simple manner.
  • the throttle element in particular high-frequency noise components during the Ab horrvorgangs be significantly reduced. By reducing the cavitation time and the so-called. Cavitation erosion is significantly reduced at the valve member and on the walls of the Ab horrraums. Cavitation erosion is caused by the imploding of gas bubbles, which in cavitation by evaporation of the fluid be formed.
  • the throttle element is arranged near the Ab horrraums.
  • the noise emissions are particularly effectively reduced.
  • the Abgresraum and the throttle element are designed so that the pump can be filled via the inlet channel even at a predetermined low pressure value in the inlet channel completely with fluid through the inlet channel within a predetermined period of time.
  • the Abgresraum and the throttle element are formed so that an end of the injection of fluid through the nozzle unit by means of the valve member is controllable, regardless of the throttle element.
  • the throttle element is formed in the form of a stepped bore of the inlet channel. This has the advantage that it is easy to manufacture.
  • At least two throttle elements are arranged in the inlet channel. This results in a further improved reduction of noise emissions.
  • the at least two throttle elements are arranged so spaced that they dampen predetermined frequencies of the pressure oscillations of the fluid in the inlet channel or transform into predetermined other frequency ranges. This results in a very effective reduction of z. B. audible to humans sound emissions.
  • a pump-nozzle device ( Figure 1) comprises a pump unit 1, a control unit 2 and a nozzle unit 5.
  • the pump-nozzle device is preferably used for supplying fuel into the combustion chamber of a cylinder of an internal combustion engine.
  • the internal combustion engine is preferably designed as a diesel internal combustion engine.
  • the internal combustion engine has an intake tract, which can be coupled by means of gas inlet valves with cylinders and is sucked in via the air.
  • the internal combustion engine further includes an exhaust tract controlled by the exhaust valve which discharges gases discharged from the cylinders.
  • the cylinders are each assigned pistons, which are each coupled via a connecting rod with a crankshaft.
  • the crankshaft is coupled to a camshaft.
  • the pump unit comprises a piston 11, a pump body 12, a pumping space 13 and a pump return means 14, which is preferably designed as a spring.
  • the piston 11 is coupled in the installed state in an internal combustion engine with a camshaft, preferably by means of a rocker arm, and is driven by this.
  • the piston 11 is guided in a recess of the pump body 12 and determined depending on its position, the volume of the pump chamber 13.
  • the pump return means 14 is formed and arranged so that the limited volume of the pump chamber 13 by the piston 13 has a maximum value no external forces on the pistons, d. H. Forces transmitted via the coupling with the camshaft act.
  • the nozzle unit 5 comprises a nozzle body 51, in which a nozzle return means 52, which is designed as a spring and possibly additionally as a damping unit, and a needle 53 are arranged.
  • the needle 53 is arranged in a recess of the nozzle body 51 and is guided in the region of a needle guide 55. In a first state, the needle 53 abuts a needle seat 54 and thus closes a nozzle 56, which for supplying the fuel into the combustion chamber of the cylinder Internal combustion engine is provided.
  • the nozzle unit 5 is preferably provided, as shown, as an inwardly opening nozzle unit.
  • the needle 53 is slightly spaced from the needle seat 54 toward the nozzle return means 52, thus releasing the nozzle 56.
  • fuel is metered into the combustion chamber of the cylinder of the internal combustion engine.
  • the first or second state is assumed depending on a force balance from the force acting on the needle 53 by the nozzle return means 52 and the counteracting force caused by the hydraulic pressure in the region of the needle heel 57.
  • the control unit comprises an inlet channel 21 and an outlet channel 22.
  • the inlet channel 21 and the outlet channel 22 can be hydraulically coupled by means of a valve.
  • the inlet channel 21 is guided from a low-pressure side connection of the pump-nozzle device to the valve.
  • the drain channel 22 is hydraulically coupled to the pumping chamber 13 and is guided to the needle hub 57 and is hydraulically coupled to the nozzle 56 depending on the condition assumed by the needle 53.
  • the valve comprises a valve member 231, which is preferably designed as a so-called.
  • a valve d. H. it opens outward against the flow direction of the fluid.
  • the valve further comprises a Abberichtraum 232 which is hydraulically coupled to the inlet channel 21 and by means of the valve member 231 with a high-pressure chamber 233 is hydraulically coupled.
  • the high pressure space 233 is hydraulically coupled to the drain passage 22.
  • valve return means 235 is provided, which is arranged and adapted to urge the valve member 231 into an open position, ie, spaced from the valve seat 234, when the forces acting on the valve member by an actuator 24 are less than the forces applied to the valve member 231 by the valve return means 235 Act.
  • the actuator 24 is preferably formed as a piezo stack. However, it can also be another actuator known to a person skilled in the art and suitable for such an application, such as an electromagnetic actuator.
  • the actuator 24 is preferably coupled to the valve member 231 by means of a transformer which preferably amplifies the stroke of the actuator 24.
  • a plug 26 for receiving electrical contacts for controlling the actuator 24 is preferably also provided.
  • valve member 231 In the open position of the valve member 231 is at a movement of the piston 11, the upward d. H. directed in the direction away from the nozzle 56, fuel sucked in via the inlet channel 21 to the pump chamber 13. As long as the valve member 231 during a subsequent downward movement of the piston 11, d. H. in a directed towards the nozzle 56 movement, is still in its open position, the fuel in the pump chamber 13 is pushed back through the valve back into the Abêtraum 232 and possibly into the inlet channel 21.
  • the needle 53 moves away from the needle seat 54 and thus outputs the nozzle 56 for the fuel supply to the cylinder of the internal combustion engine free.
  • the needle 53 then moves back into the needle seat 54 and thus closes the nozzle 56 when the hydraulic pressure in the drain passage 22 falls below the value at which the force caused by the hydraulic pressure at the needle heel 57 is less than that caused by the nozzle return means 52 Force.
  • the time at which this value is exceeded and at which thus the fuel metering is terminated, can be influenced by the control of the valve member 231 from its closed position to an open position.
  • the hydraulic coupling between the high pressure chamber 233 and the Abêtraum 232 and the inlet channel 21 is made. Due to the high pressure difference prevailing during opening between the fluid in the high-pressure chamber 233 and the fluid in the discharge chamber 232 and the inlet channel 21, the fuel then flows from the high-pressure space 233 at a very high speed, as a rule with the current speed of sound of the fluid to be injected As a result, the pressure in the high-pressure chamber 233, in the pump chamber 13 and the outlet channel 22 is rapidly reduced so much that the forces acting on the needle 53 by the nozzle return means 52 lead to the needle 53 moves into the needle seat 54 and thus then closes the nozzle 56.
  • a throttle element 27 is arranged in the inlet channel 21 ( Figure 2).
  • the throttle element 27 causes a rapid increase in pressure in the Abgresraum 232 and slows the flow of fuel into the inlet channel 21.
  • the throttle element in particular high-frequency noise components during the Abêtvorgangs be significantly reduced.
  • the cavitation time i. H. the time during which the fuel flows from the high-pressure chamber 233 to the Abgresraum 232 at the speed of sound and at the vapor bubbles form, which then implode again in a region of lower flow velocity and thereby generate sound and cause damage to the valve body, greatly reduced.
  • the generation of sound emissions is easily attenuated in a simple manner.
  • the throttle element 27 in particular higher-frequency noise components during the Ab horrvorgangs be significantly reduced.
  • the throttle element 27 is preferably arranged very close to the diversion chamber 232, as shown in FIG. The closer the throttle element 27 is arranged to the diversion chamber, the more effectively the noise emissions are reduced.
  • a sealing connection between the inlet channel 21 and a fuel supply device associated therewith, which usually takes place by means of an O-ring, is also spared and thus increases its service life.
  • the throttle element is particularly easily produced by a stepped bore. For this purpose, preferably first a pilot hole and the holes can then be rounded hydroerosive. In the hydroerosive rounding particles present in a fluid cause the rounding of the given Areas.
  • the throttle element 27 may also be used as an insert in the inlet channel 21.
  • At least two throttle elements 60, 61, 62, 63 are arranged in the inlet channel 21.
  • predetermined frequencies of the pressure oscillations of the fuel in the inlet channel 21 can be specifically damped or transformed into predetermined other, preferably not audible to humans, frequency ranges.
  • the throttle elements 60 to 63 interact with the inlet channel 21 as resonators and each reflect pressure waves having a predetermined wavelength, so that the corresponding wave dissipates.
  • the throttle element or elements 27, 60 to 63 and the diversion chamber are designed so that the pump chamber 13 can be filled via the inlet channel 21 even at a predetermined low pressure value, preferably 3 to 10 bar in the inlet channel 21 within a predetermined period of time is.
  • the predetermined time is chosen depending on the speed of the crankshaft. This then ensures that the operation of the pump-nozzle device, d. H. the earliest possible start of injection and the maximum possible injection quantity by the throttle element (s) 27; 60 to 63 are not affected.
  • the solid line in Figure 4 shows an exemplary pressure curve in a pump-nozzle device according to Figure 2 in the drain passage 22.
  • the threshold value pthr of the pressure is exceeded and thus the fuel metering begins in the cylinder, as in Figure 5 is plotted over the time t, based on the metered amount of fuel Qinj.
  • the threshold value pthr of the pressure is then fallen below again and thus the fuel metering is ended.
  • the throttle element 27 is formed and arranged, and also the Abschraum 27 is formed so that compared to a pump-nozzle device without the throttle element 27, the pressure drop at pressures above the threshold value p thr is identical (see dashed line of pressure).
  • the pressure curve is shown for the case in which the throttle element 27 is dimensioned so that at the predetermined low pressure value no complete filling of the pump chamber 13 is ensured.
  • the pressure build-up in the pump chamber 13 takes place only delayed and the threshold value pthr is reached only at the time t2.
  • the throttle element 27 is dimensioned in this case so that after a Abêtn of the valve by the throttle effect of the throttle element 27, the pressure already above the threshold value p thr slower than in the unthrottled case. This In addition to the consequence that also the end of the fuel metering occurs only delayed at time t5.
  • the dot-dashed line continues the course of the dotted line in the event that the throttle element 27 is dimensioned so that its throttling action leads to a change in the pressure drop only below the threshold value p thr compared to the unthrottled case.

Description

Die Erfindung betrifft eine Pumpe-Düse-Vorrichtung mit einer Pumpe, einem Ventil und einer Düseneinheit. Derartige Pumpe-Düse-Vorrichtungen werden insbesondere zur Kraftstoffzufuhr in einen Brennraum einer direkteinspritzenden Brennkraftmaschine, insbesondere einer Diesel-Brennkraftmaschine eingesetzt. Die Pumpe, eine Steuereinheit, die neben dem Ventil auch einen Stellantrieb umfasst, welche vorzugsweise aus einem Piezostapel gebildet ist, und die Düseneinheit bilden eine Baueinheit. Der Antrieb eines Kolbens der Pumpe erfolgt vorzugsweise über eine Nockenwelle einer Brennkraftmaschine mittels eines Kipphebels. Die Pumpe ist über das Ventil an eine Niederdruck-Kraftstoffzuführeinrichtung hydraulisch koppelbar. Sie ist ausgangsseitig mit der Düseneinheit hydraulisch gekoppelt. Einspritzbeginn und Einspritzmenge werden durch das Ventil und dessen Stellantrieb bestimmt. Durch die kompakte Bauweise der Pumpe-Düse-Vorrichtung ergibt sich ein sehr geringes Hochdruckvolumen und eine große hydraulische Steifigkeit. Es werden so sehr hohe Einspritzdrücke von ca. 2.000 bar ermöglicht. Dieser hohe Einspritzdruck in Verbindung mit der guten Steuerbarkeit des Einspritzbeginns und der Einspritzmenge ermöglichen eine deutliche Reduktion der Emissionen bei gleichzeitig niedrigen Kraftstoffverbrauch beim Einsatz in Brennkraftmaschinen.The invention relates to a pump-nozzle device with a pump, a valve and a nozzle unit. Such pump-nozzle devices are used in particular for supplying fuel into a combustion chamber of a direct-injection internal combustion engine, in particular a diesel internal combustion engine. The pump, a control unit which also includes an actuator in addition to the valve, which is preferably formed from a piezo stack, and the nozzle unit form a structural unit. The drive of a piston of the pump is preferably via a camshaft of an internal combustion engine by means of a rocker arm. The pump can be hydraulically coupled via the valve to a low-pressure fuel supply device. It is hydraulically coupled on the output side with the nozzle unit. Start of injection and injection quantity are determined by the valve and its actuator. Due to the compact design of the pump-nozzle device results in a very low volume of high pressure and high hydraulic stiffness. This enables very high injection pressures of approx. 2,000 bar. This high injection pressure in conjunction with the good controllability of the start of injection and the injection quantity allow a significant reduction in emissions while low fuel consumption when used in internal combustion engines.

Aus der DE 198 35 494 C2 ist eine Pumpe-Düse-Vorrichtung bekannt mit einer Pumpe und einem Ventil mit einem Ventilglied, das die hydraulische Kopplung eines Absteuerraums mit einem Ablaufkanal steuert. Der Ablaufkanal ist hydraulisch gekoppelt mit der Pumpe und einer Düseneinheit. Ein Zulaufkanal ist vorgesehen der hydraulisch gekoppelt ist mit dem Absteuerraum. Dem Ventilglied ist ein piezoelektrischer Stellantrieb zugeordnet, über den das Ventilglied zwischen zwei Endstellungen verstellt werden kann. In einer ersten Endstellung des Ventilglieds ist der Ablaufkanal hydraulisch gekoppelt mit einem Absteuerraum und dieser wiederum mit dem Zulaufkanal. In einer zweiten Endstellung des Ventilglieds ist der Ablaufkanal hydraulisch entkoppelt von dem Absteuerraum. In der ersten Endstellung des Ventilglieds wird während eines Förderhubs der Pumpe Fluid von dem Zulaufkanal über den Absteuerraum und den Ablaufkanal von der Pumpe angesaugt. Während eines Arbeitshubs eines Pumpenkolbens der Pumpe wird in der ersten Endposition des Ventilglieds Fluid von der Pumpe über den Zulaufkanal, den Absteuerraum in den Ablaufkanal zurückgedrückt. In der zweiten Endposition des Ventilglieds kann während des Förderhubs des Pumpenkolbens wegen der fehlenden hydraulischen Kopplung des Ablaufkanals mit dem Absteuerraum und dem Ablaufkanal kein Fluid zurückgedrückt werden und der Pumpenkolben erzeugt Hochdruck. Mit Überschreiten einer vorgegebenen Druckschwelle öffnet eine Düsennadel der Düseneinheit eine Düse der Düseneinheit und es erfolgt eine Einspritzung des Fluids. Das Einspritzende wird dadurch bestimmt, dass das Ventilglied mittels des Stellantriebs in seine erste Endposition gesteuert wird und so Fluid über den Ablaufkanal in den Absteuerraum und den Zulaufkanal zurückströmen kann, was zur Folge hat, dass der Druck in der Pumpe und somit auch in der Düseneinheit abnimmt, was wiederum zu einem Schließen der Düseneinheit führt. Bei diesem sog. Absteuervorgang werden hohe Geräuschemissionen erzeugt. Derartige Geräuschemissionen werden vom Fahrer eines Kraftfahrzeugs, in dem die Pumpe-Düse-Vorrichtung eingebaut sein kann, als unangenehm wahrgenommen und müssen zum einen im Hinblick auf einen möglichst hohen Fahrkomfort und zum anderen auch aufgrund immer strengerer gesetzlicher Bestimmungen bezüglich Geräuschemissionen von Fahrzeugen weitgehend vermieden werden.From the DE 198 35 494 C2 For example, a pump-nozzle device is known comprising a pump and a valve having a valve member which controls the hydraulic coupling of a spill space to a drain passage. The drainage channel is hydraulically coupled to the pump and a nozzle unit. An inlet channel is provided which is hydraulically coupled to the Absteuerraum. The valve member is associated with a piezoelectric actuator, via which the valve member between two end positions can be adjusted. In a first end position of the valve member of the flow channel is hydraulically coupled to a Absteuerraum and this in turn with the inlet channel. In a second end position of the valve member of the flow channel is hydraulically decoupled from the Absteuerraum. In the first end position of the valve member during a delivery stroke of the pump fluid is sucked from the inlet channel via the Absteuerraum and the drainage passage of the pump. During a working stroke of a pump piston of the pump in the first end position of the valve member fluid from the pump via the inlet channel, the spill chamber is pushed back into the drain channel. In the second end position of the valve member, no fluid can be pushed back during the delivery stroke of the pump piston because of the lack of hydraulic coupling of the drain channel with the Absteuerraum and the drain channel and the pump piston generates high pressure. When a predetermined pressure threshold is exceeded, a nozzle needle of the nozzle unit opens a nozzle of the nozzle unit and there is an injection of the fluid. The end of injection is determined by controlling the valve member to its first end position by means of the actuator and thus allowing fluid to flow back into the discharge chamber and the inlet channel via the discharge channel, with the result that the pressure in the pump and thus also in the nozzle unit decreases, which in turn leads to a closing of the nozzle unit. In this so-called. Absteuervorgang high noise emissions are generated. Such noise emissions are perceived as unpleasant by the driver of a motor vehicle, in which the pump-nozzle device can be installed and must be largely avoided on the one hand in terms of the highest possible ride comfort and on the other due to increasingly stringent statutory provisions regarding noise emissions from vehicles ,

Die US 2002/0113140 A1 offenbart eine Pumpe-Düse-Vorrichtung mit einem über einen hydraulischen Übersetzter piezoelektrisch betätigbaren Steuerventil, das zur Steuerung einer Voreinspritzung mit einem Drosselabschnitt ausgebildet ist. Durch den Drosselabschnitt kann eine Ansteuerung eines Ventilglieds des Steuerventils ungenauer erfolgen, wobei trotzdem eine Voreinspritzung zuverlässig gesteuert erfolgen kann.The US 2002/0113140 A1 discloses a pump-nozzle device with a piezoelectric actuated control valve via a hydraulic translator, which is used to control a pre-injection is formed with a throttle portion. Through the throttle section, a control of a valve member of the control valve can be made less accurate, while still a pre-injection can be controlled reliably.

Die Aufgabe der Erfindung ist es, eine Pumpe-Düse-Vorrichtung zu schaffen, welche geringe Geräuschemissionen gewährleistet beim Betrieb.The object of the invention is to provide a pump-nozzle device which ensures low noise emissions during operation.

Die Aufgabe wird gelöst durch die Merkmale des unabhängigen Patentanspruchs. Vorteilhafte Weiterbildungen der Erfindung sind in den Unteransprüchen gekennzeichnet.The object is solved by the features of the independent claim. Advantageous developments of the invention are characterized in the subclaims.

Die Erfindung beruht auf der Erkenntnis, dass die während des Betriebs der Pumpe-Düse-Vorrichtung nach dem Stand der Technik hervorgerufenen Geräuschemissionen im Wesentlichen verursacht sind durch Kavitation nach dem Herstellen der hydraulischen Kopplung zwischen dem Ablaufkanal mit unter Hochdruck stehendem Fluid und dem Absteuerraum und dem Ablaufkanal. Der entstehende Absteuerimpuls führt zu Druckwellen hoher Amplitude in dem Fluid im Bereich des Absteuerraums und des Zuführkanals, die in Form von Schallwellen aus der Pumpe-Düse-Vorrichtung nach außen übertragen werden.The invention is based on the recognition that the noise emissions caused during the operation of the prior art pump-nozzle device are essentially caused by cavitation after establishing the hydraulic coupling between the high-pressure fluid drainage channel and the discharge chamber and the drain channel. The resulting Absteuerimpuls leads to high-amplitude pressure waves in the fluid in the region of the Absteuerraums and the feed channel, which are transmitted in the form of sound waves from the pump-nozzle device to the outside.

Die Erfindung zeichnet sich dadurch aus, dass in dem Zulaufkanal ein Drosselelement vorgesehen ist. Das Drosselelement bewirkt einen schnellen Druckanstieg in dem Absteuerraum und verlangsamt das Abströmen des Fluids in den Zulaufkanal. Dadurch wird die Zeitdauer, innerhalb derer Kavitation auftritt stark verringert und so die Erzeugung von Schallemissionen auf einfache Weise stark gedämpft. Durch das Drosselelement werden insbesondere hochfrequente Geräuschanteile während des Absteuervorgangs deutlich reduziert. Durch das Verringern der Kavitationszeit wird auch die sog. Kavitationserosion an dem Ventilglied und an den Wänden des Absteuerraums deutlich verringert. Kavitationserosion entsteht durch das Implodieren von Gasbläschen, die bei Kavitation durch Verdampfen des Fluids gebildet werden. Während der Zeitdauer, innerhalb derer Kavitation im Bereich des Ventilglieds auftritt ist der Druckverlauf auf die verschiedenen Ventilflächen des Ventilglieds äußerst instationär und eine präzise Einstellung der Position des Ventilglieds somit schwer realisierbar. Somit bewirkt die Verringerung der Kavitationszeit, die hervorgerufen ist durch das Drosselelement, auch eine präzisere Ansteuerung des Ventilglieds.The invention is characterized in that a throttle element is provided in the inlet channel. The throttle element causes a rapid increase in pressure in the Absteuerraum and slows the outflow of fluid into the inlet channel. This greatly reduces the amount of time that cavitation occurs, thereby greatly attenuating the generation of sound emissions in a simple manner. The throttle element in particular high-frequency noise components during the Absteuervorgangs be significantly reduced. By reducing the cavitation time and the so-called. Cavitation erosion is significantly reduced at the valve member and on the walls of the Absteuerraums. Cavitation erosion is caused by the imploding of gas bubbles, which in cavitation by evaporation of the fluid be formed. During the period of time within which cavitation occurs in the region of the valve member, the pressure profile on the various valve surfaces of the valve member is extremely unsteady and a precise adjustment of the position of the valve member thus difficult to achieve. Thus, the reduction in the cavitation time caused by the throttle element also causes a more precise control of the valve member.

In einer vorteilhaften Ausgestaltung der Erfindung ist das Drosselelement nahe des Absteuerraums angeordnet. So werden die Geräuschemissionen besonders wirksam verringert. Ferner wird auch so eine dichtende Verbindung zwischen dem Zulaufkanal und einer diesem zugeordneten Kraftstoffzufuhreinrichtung, die üblicherweise mittels eines O-Rings erfolgt geschont und somit deren Lebensdauer erhöht.In an advantageous embodiment of the invention, the throttle element is arranged near the Absteuerraums. Thus, the noise emissions are particularly effectively reduced. Furthermore, a sealing connection between the inlet channel and a fuel supply device associated with it, which is usually protected by means of an O-ring, thus also increases its service life.

In einer weiteren vorteilhaften Ausgestaltung der Erfindung sind der Absteuerraum und das Drosselelement so ausgebildet, dass die Pumpe über den Zulaufkanal auch bei einem vorgegebenen Niederdruckwert in dem Zulaufkanal vollständig mit Fluid über den Zulaufkanal innerhalb einer vorgegebenen Zeitdauer befüllbar ist. Dies hat den Vorteil, dass dann der Betrieb der Pumpe-Düse-Vorrichtung, d. h. der frühestmögliche Einspritzbeginn und die maximal mögliche Einspritzmenge durch das Drosselelement nicht beeinflusst sind.In a further advantageous embodiment of the invention, the Absteuerraum and the throttle element are designed so that the pump can be filled via the inlet channel even at a predetermined low pressure value in the inlet channel completely with fluid through the inlet channel within a predetermined period of time. This has the advantage that then the operation of the pump-nozzle device, d. H. the earliest possible start of injection and the maximum possible injection quantity are not influenced by the throttle element.

In einer weiteren vorteilhaften Ausgestaltung der Erfindung sind der Absteuerraum und das Drosselelement so ausgebildet, dass ein Ende des Einspritzens von Fluid über die Düseneinheit mittels des Ventilglieds steuerbar ist und zwar unabhängig von dem Drosselelement. Dies hat den Vorteil, dass das Verringern der Geräuschemissionen nicht zu einer Beeinflussung des möglichen Endes des Einspritzens führt. Das Drosselelement beeinflusst somit das Ende der Einspritzung nicht.In a further advantageous embodiment of the invention, the Absteuerraum and the throttle element are formed so that an end of the injection of fluid through the nozzle unit by means of the valve member is controllable, regardless of the throttle element. This has the advantage that reducing the noise emissions does not affect the possible end of the injection. The throttle element thus does not affect the end of the injection.

In einer weiteren vorteilhaften Ausgestaltung der Erfindung ist das Drosselelement in Form einer Stufenbohrung des Zulaufkanals gebildet. Dies hat den Vorteil, dass es einfach herzustellen ist.In a further advantageous embodiment of the invention, the throttle element is formed in the form of a stepped bore of the inlet channel. This has the advantage that it is easy to manufacture.

In einer weiteren vorteilhaften Ausgestaltung der Erfindung sind mindestens zwei Drosselelemente in dem Zulaufkanal angeordnet. Dadurch ergibt sich ein nochmals verbessertes Verringern der Geräuschemissionen.In a further advantageous embodiment of the invention, at least two throttle elements are arranged in the inlet channel. This results in a further improved reduction of noise emissions.

In einer weiteren vorteilhaften Ausgestaltung der Erfindung sind die mindestens zwei Drosselelemente so beabstandet angeordnet, dass sie vorgegebene Frequenzen der Druckschwingungen des Fluids in dem Zulaufkanal dämpfen oder in vorgegebene andere Frequenzbereiche transformieren. Dadurch ergibt sich ein sehr wirksames Verringern von z. B. für den Mensch hörbaren Schallemissionen.In a further advantageous embodiment of the invention, the at least two throttle elements are arranged so spaced that they dampen predetermined frequencies of the pressure oscillations of the fluid in the inlet channel or transform into predetermined other frequency ranges. This results in a very effective reduction of z. B. audible to humans sound emissions.

Ausführungsbeispiele der Erfindung werden im Folgenden anhand der schematischen Zeichnungen erläutert. Es zeigen:

Figur 1
ein erstes Ausführungsbeispiel einer Pumpe-Düse-Vorrichtung,
Figur 2
eine Ausschnittsvergrößerung der Pumpe-Düse-Vorrichtung gemäß Figur 1,
Figur 3
ein zweites Ausführungsbeispiel der Pumpe-Düse-Vorrichtung,
Figur 4
den Verlauf des Drucks innerhalb des Hochdruckbereichs der Pumpe-Düse-Vorrichtung aufgetragen über die Zeit t und
Figur 5
der eingespritzte Kraftstoffmassenstrom Qinj aufgetragen über die Zeit t.
Embodiments of the invention are explained below with reference to the schematic drawings. Show it:
FIG. 1
A first embodiment of a pump-nozzle device,
FIG. 2
an enlarged detail of the pump-nozzle device according to Figure 1,
FIG. 3
A second embodiment of the pump-nozzle device,
FIG. 4
the course of the pressure within the high pressure region of the pump-nozzle device over the time t and
FIG. 5
the injected fuel mass flow Qinj is plotted over time t.

Elemente gleicher Konstruktion und Funktion sind figurenübergreifend mit den gleichen Bezugszeichen versehen.Elements of the same construction and function are provided across the figures with the same reference numerals.

Eine Pumpe-Düse-Vorrichtung (Figur 1) umfasst eine Pumpeneinheit 1, eine Steuereinheit 2 und eine Düseneinheit 5. Die Pumpe-Düse-Vorrichtung wird bevorzugt eingesetzt zum Zuführen von Kraftstoff in den Brennraum eines Zylinders einer Brennkraftmaschine. Die Brennkraftmaschine ist vorzugsweise als Diesel-Brennkraftmaschine ausgebildet. Die Brennkraftmaschine hat einen Ansaugtrakt, der mittels Gaseinlassventilen mit Zylindern koppelbar ist und über die Luft angesaugt wird. Die Brennkraftmaschine weist ferner einen Abgastrakt auf, der über das Auslassventil gesteuert, die aus den Zylindern auszustoßenden Gase abführt. Den Zylindern sind jeweils Kolben zugeordnet, die jeweils über eine Pleuelstange mit einer Kurbelwelle gekoppelt sind. Die Kurbelwelle ist mit einer Nockenwelle gekoppelt.A pump-nozzle device (Figure 1) comprises a pump unit 1, a control unit 2 and a nozzle unit 5. The pump-nozzle device is preferably used for supplying fuel into the combustion chamber of a cylinder of an internal combustion engine. The internal combustion engine is preferably designed as a diesel internal combustion engine. The internal combustion engine has an intake tract, which can be coupled by means of gas inlet valves with cylinders and is sucked in via the air. The internal combustion engine further includes an exhaust tract controlled by the exhaust valve which discharges gases discharged from the cylinders. The cylinders are each assigned pistons, which are each coupled via a connecting rod with a crankshaft. The crankshaft is coupled to a camshaft.

Die Pumpeneinheit umfasst einen Kolben 11, einen Pumpenkörper 12, einen Pumpraum 13 und ein Pumpen-Rückstellmittel 14, das vorzugsweise als Feder ausgebildet ist. Der Kolben 11 ist im eingebauten Zustand in einer Brennkraftmaschine mit einer Nockenwelle gekoppelt, vorzugsweise mittels eines Kipphebels, und wird von dieser angetrieben. Der Kolben 11 ist in einer Ausnehmung des Pumpenkörpers 12 geführt und bestimmt abhängig von seiner Position das Volumen des Pumpraums 13. Das Pumpen-Rückstellmittel 14 ist so ausgebildet und angeordnet, dass das durch den Kolben 11 begrenzte Volumen des Pumpraums 13 einen Maximalwert aufweist, wenn auf den Kolben keine äußeren Kräfte, d. h. Kräfte, die über die Kopplung mit der Nockenwelle übertragen werden, einwirken.The pump unit comprises a piston 11, a pump body 12, a pumping space 13 and a pump return means 14, which is preferably designed as a spring. The piston 11 is coupled in the installed state in an internal combustion engine with a camshaft, preferably by means of a rocker arm, and is driven by this. The piston 11 is guided in a recess of the pump body 12 and determined depending on its position, the volume of the pump chamber 13. The pump return means 14 is formed and arranged so that the limited volume of the pump chamber 13 by the piston 13 has a maximum value no external forces on the pistons, d. H. Forces transmitted via the coupling with the camshaft act.

Die Düseneinheit 5 umfasst einen Düsenkörper 51, in dem ein Düsenrückstellmittel 52, das als Feder und ggf. zusätzlich als Dämpfungseinheit ausgebildet ist, und eine Nadel 53 angeordnet sind. Die Nadel 53 ist in einer Ausnehmung des Düsenkörpers 51 angeordnet und wird im Bereich einer Nadelführung 55 geführt. In einem ersten Zustand liegt die Nadel 53 an einem Nadelsitz 54 an und verschließt so eine Düse 56, die zum Zuführen des Kraftstoffs in den Brennraum des Zylinders der Brennkraftmaschine vorgesehen ist. Die Düseneinheit 5 ist vorzugsweise, wie dargestellt, als nach innen öffnende Düseneinheit vorgesehen.The nozzle unit 5 comprises a nozzle body 51, in which a nozzle return means 52, which is designed as a spring and possibly additionally as a damping unit, and a needle 53 are arranged. The needle 53 is arranged in a recess of the nozzle body 51 and is guided in the region of a needle guide 55. In a first state, the needle 53 abuts a needle seat 54 and thus closes a nozzle 56, which for supplying the fuel into the combustion chamber of the cylinder Internal combustion engine is provided. The nozzle unit 5 is preferably provided, as shown, as an inwardly opening nozzle unit.

In einem zweiten Zustand ist die Nadel 53 leicht beabstandet zu dem Nadelsitz 54 und zwar hin in Richtung zu dem Düsenrückstellmittel 52 angeordnet und gibt so die Düse 56 frei. In diesem zweiten Zustand wird Kraftstoff in den Brennraum des Zylinders der Brennkraftmaschine zugemessen. Der erste oder zweite Zustand wird eingenommen abhängig von einer Kräftebilanz aus der Kraft, die durch das Düsenrückstellmittel 52 auf die Nadel 53 wirkt und aus der dieser entgegenwirkenden Kraft, die durch den hydraulischen Druck im Bereich des Nadelabsatzes 57 hervorgerufen wird.In a second condition, the needle 53 is slightly spaced from the needle seat 54 toward the nozzle return means 52, thus releasing the nozzle 56. In this second state, fuel is metered into the combustion chamber of the cylinder of the internal combustion engine. The first or second state is assumed depending on a force balance from the force acting on the needle 53 by the nozzle return means 52 and the counteracting force caused by the hydraulic pressure in the region of the needle heel 57.

Die Steuereinheit umfasst einen Zulaufkanal 21 und einen Ablaufkanal 22. Der Zulaufkanal 21 und der Ablaufkanal 22 sind mittels eines Ventils hydraulisch koppelbar. Der Zulaufkanal 21 ist von einem niederdruckseitigen Anschluss der Pumpe-Düse-Vorrichtung hin zu dem Ventil geführt. Der Ablaufkanal 22 ist hydraulisch mit dem Pumpraum 13 gekoppelt und ist hin zu dem Nadelabsatz 57 geführt und ist hydraulisch abhängig von dem Zustand, der von der Nadel 53 eingenommen wird, mit der Düse 56 koppelbar.The control unit comprises an inlet channel 21 and an outlet channel 22. The inlet channel 21 and the outlet channel 22 can be hydraulically coupled by means of a valve. The inlet channel 21 is guided from a low-pressure side connection of the pump-nozzle device to the valve. The drain channel 22 is hydraulically coupled to the pumping chamber 13 and is guided to the needle hub 57 and is hydraulically coupled to the nozzle 56 depending on the condition assumed by the needle 53.

Das Ventil umfasst ein Ventilglied 231, das vorzugsweise als sog. A-Ventil ausgebildet ist, d. h. es öffnet nach außen entgegen der Strömungsrichtung des Fluids. Das Ventil umfasst ferner einen Absteuerraum 232, der hydraulisch gekoppelt ist mit dem Zulaufkanal 21 und mittels des Ventilglieds 231 mit einem Hochdruckraum 233 hydraulisch koppelbar ist. Der Hochdruckraum 233 ist hydraulisch gekoppelt mit dem Ablaufkanal 22.The valve comprises a valve member 231, which is preferably designed as a so-called. A valve, d. H. it opens outward against the flow direction of the fluid. The valve further comprises a Absteuerraum 232 which is hydraulically coupled to the inlet channel 21 and by means of the valve member 231 with a high-pressure chamber 233 is hydraulically coupled. The high pressure space 233 is hydraulically coupled to the drain passage 22.

In der geschlossenen Stellung des Ventilglieds 231 liegt das Ventilglied 231 an einem Ventilsitz 234 eines Ventilkörpers 237 an. Ferner ist ein Ventilrückstellmittel 235 vorgesehen, welches so angeordnet und ausgebildet ist, dass es das Ventilglied 231 in eine Offenstellung, d. h. beabstandet zu dem Ventilsitz 234 drückt, wenn die durch einen Stellantrieb 24 auf das Ventilglied wirkenden Kräfte geringer sind als die Kräfte, die durch das Ventilrückstellmittel 235 auf das Ventilglied 231 wirken. Der Stellantrieb 24 ist vorzugsweise als Piezostapel ausgebildet. Er kann jedoch auch ein anderer dem Fachmann bekannter und für eine derartige Anwendung geeigneter Stellantrieb, wie ein elektromagnetischer Stellantrieb sein.In the closed position of the valve member 231, the valve member 231 abuts against a valve seat 234 of a valve body 237. Furthermore, a valve return means 235 is provided, which is arranged and adapted to urge the valve member 231 into an open position, ie, spaced from the valve seat 234, when the forces acting on the valve member by an actuator 24 are less than the forces applied to the valve member 231 by the valve return means 235 Act. The actuator 24 is preferably formed as a piezo stack. However, it can also be another actuator known to a person skilled in the art and suitable for such an application, such as an electromagnetic actuator.

Der Stellantrieb 24 ist vorzugsweise mittels eines Übertragers, der vorzugsweise den Hub des Stellantriebs 24 verstärkt, mit dem Ventilglied 231 gekoppelt. An dem Stellantrieb 24 ist vorzugsweise auch ein Stecker 26 zur Aufnahme von elektrischen Kontakten zur Ansteuerung des Stellantriebs 24 vorgesehen.The actuator 24 is preferably coupled to the valve member 231 by means of a transformer which preferably amplifies the stroke of the actuator 24. On the actuator 24, a plug 26 for receiving electrical contacts for controlling the actuator 24 is preferably also provided.

In der Offenstellung des Ventilglieds 231 wird bei einer Bewegung des Kolbens 11, die nach oben d. h. in Richtung weg von der Düse 56 gerichtet ist, Kraftstoff über den Zulaufkanal 21 hin zum Pumpraum 13 angesaugt. Solange das Ventilglied 231 während einer anschließenden Abwärtsbewegung des Kolbens 11, d. h. bei einer hin zu der Düse 56 gerichteten Bewegung, weiterhin in seiner Offenstellung befindet, wird der in dem Pumpraum 13 befindliche Kraftstoff über das Ventil wieder zurück in den Absteuerraum 232 und ggf. in den Zulaufkanal 21 zurückgedrückt.In the open position of the valve member 231 is at a movement of the piston 11, the upward d. H. directed in the direction away from the nozzle 56, fuel sucked in via the inlet channel 21 to the pump chamber 13. As long as the valve member 231 during a subsequent downward movement of the piston 11, d. H. in a directed towards the nozzle 56 movement, is still in its open position, the fuel in the pump chamber 13 is pushed back through the valve back into the Absteuerraum 232 and possibly into the inlet channel 21.

Sobald jedoch bei der Abwärtsbewegung des Kolbens 11 das Ventilglied 231 in seine geschlossene Stellung gesteuert ist, wird der im Pumpraum 13 und somit auch der im Ablaufkanal 22 und der in dem Hochdruckraum 233 befindliche Kraftstoff verdichtet, wodurch der Druck mit zunehmender Abwärtsbewegung des Kolbens 11 im Pumpraum 13, im Hochdruckraum 233 und im Ablaufkanal 22 zunimmt. Entsprechend dem steigenden Druck im Ablaufkanal 22 erhöht sich auch die durch den Hydraulikdruck hervorgerufene Kraft, die auf den Nadelabsatz 57 in Richtung einer Öffnungsbewegung der Nadel 53 zum Freigeben der Düse 56 wirkt. Wenn der Druck in dem Ablaufkanal 22 einen Wert überschreitet, bei dem die durch den Hydraulikdruck hervorgerufene Kraft auf den Nadelabsatz 57 größer ist als die dieser entgegenwirkende Kraft des Düsenrückstellmittels 52, bewegt sich die Nadel 53 weg vom Nadelsitz 54 und gibt so die Düse 56 für die Kraftstoffzufuhr zum Zylinder der Brennkraftmaschine frei. Die Nadel 53 bewegt sich dann wieder hinein in den Nadelsitz 54 und verschließt somit die Düse 56, wenn der Hydraulikdruck in dem Ablaufkanal 22 den Wert unterschreitet, bei dem die durch den Hydraulikdruck am Nadelabsatz 57 hervorgerufene Kraft kleiner ist als die durch das Düsenrückstellmittel 52 hervorgerufene Kraft. Der Zeitpunkt, an dem dieser Wert unterschritten wird und an dem somit die Kraftstoffzumessung beendet wird, kann durch das Steuern des Ventilglieds 231 von seiner geschlossenen Stellung in eine Offenstellung beeinflusst werden.However, as soon as the valve member 231 is controlled in its closed position during the downward movement of the piston 11, the fuel in the pump chamber 13 and thus also in the outlet channel 22 and in the high pressure chamber 233 is compressed, whereby the pressure with increasing downward movement of the piston 11 in Pumping chamber 13, in the high-pressure chamber 233 and in the drain passage 22 increases. In accordance with the increasing pressure in the outlet channel 22, the pressure increased by the hydraulic pressure caused force acting on the needle shoulder 57 in the direction of an opening movement of the needle 53 to release the nozzle 56. When the pressure in the drain passage 22 exceeds a value at which the force on the needle hub 57 caused by the hydraulic pressure is greater than the counteracting force of the nozzle return means 52, the needle 53 moves away from the needle seat 54 and thus outputs the nozzle 56 for the fuel supply to the cylinder of the internal combustion engine free. The needle 53 then moves back into the needle seat 54 and thus closes the nozzle 56 when the hydraulic pressure in the drain passage 22 falls below the value at which the force caused by the hydraulic pressure at the needle heel 57 is less than that caused by the nozzle return means 52 Force. The time at which this value is exceeded and at which thus the fuel metering is terminated, can be influenced by the control of the valve member 231 from its closed position to an open position.

Durch das Steuern des Ventilglieds von seiner Schließstellung in seine Offenstellung wird die hydraulische Kopplung zwischen dem Hochdruckraum 233 und dem Absteuerraum 232 und dem Zulaufkanal 21 hergestellt. Aufgrund des beim Öffnen herrschenden hohen Druckunterschieds zwischen dem Fluid in dem Hochdruckraum 233 und dem Fluid in dem Absteuerraum 232 und dem Zulaufkanal 21 strömt dann der Kraftstoff von dem Hochdruckraum 233 mit sehr hoher Geschwindigkeit, in der Regel mit der aktuellen Schallgeschwindigkeit des einzuspritzenden Fluids, in den Absteuerraum 232 und weiter in den Zulaufkanal 21. Dadurch wird dann der Druck in dem Hochdruckraum 233, in dem Pumpraum 13 und dem Ablaufkanal 22 schnell so stark verringert, dass die von dem Düsenrückstellmittel 52 auf die Nadel 53 wirkenden Kräfte dazu führen, dass sich die Nadel 53 in den Nadelsitz 54 bewegt und somit dann die Düse 56 verschließt.By controlling the valve member from its closed position to its open position, the hydraulic coupling between the high pressure chamber 233 and the Absteuerraum 232 and the inlet channel 21 is made. Due to the high pressure difference prevailing during opening between the fluid in the high-pressure chamber 233 and the fluid in the discharge chamber 232 and the inlet channel 21, the fuel then flows from the high-pressure space 233 at a very high speed, as a rule with the current speed of sound of the fluid to be injected As a result, the pressure in the high-pressure chamber 233, in the pump chamber 13 and the outlet channel 22 is rapidly reduced so much that the forces acting on the needle 53 by the nozzle return means 52 lead to the needle 53 moves into the needle seat 54 and thus then closes the nozzle 56.

In dem Zulaufkanal 21 (Figur 2) ist ein Drosselelement 27 angeordnet. Das Drosselelement 27 bewirkt einen schnellen Druckanstieg in dem Absteuerraum 232 und verlangsamt das Abströmen des Kraftstoffs in den Zulaufkanal 21. Dadurch wird die Zeitdauer, innerhalb derer Kavitation auftritt, stark verringert und so die Erzeugung von Schallemissionen auf einfache Weise stark gedämpft. Durch das Drosselelement werden insbesondere hochfrequente Geräuschanteile während des Absteuervorgangs deutlich reduziert. Durch das Verringern der Kavitationszeit, d. h. der Zeit während der Kraftstoff vom Hochdruckraum 233 hin zu dem Absteuerraum 232 mit Schallgeschwindigkeit strömt und bei der sich Dampfblasen bilden, die dann in einem Bereich geringerer Strömungsgeschwindigkeit wieder implodieren und dabei Schall erzeugen und auch Beschädigungen am Ventilkörper hervorrufen, stark verringert. So wird das Erzeugen von Schallemissionen auf einfache Weise stark gedämpft.In the inlet channel 21 (Figure 2), a throttle element 27 is arranged. The throttle element 27 causes a rapid increase in pressure in the Absteuerraum 232 and slows the flow of fuel into the inlet channel 21. Thus, the period of time within which cavitation occurs, greatly reduced, and thus greatly attenuates the generation of acoustic emissions in a simple manner. The throttle element in particular high-frequency noise components during the Absteuervorgangs be significantly reduced. By reducing the cavitation time, i. H. the time during which the fuel flows from the high-pressure chamber 233 to the Absteuerraum 232 at the speed of sound and at the vapor bubbles form, which then implode again in a region of lower flow velocity and thereby generate sound and cause damage to the valve body, greatly reduced. Thus, the generation of sound emissions is easily attenuated in a simple manner.

Durch das Drosselelement 27 werden insbesondere höherfrequente Geräuschanteile während des Absteuervorgangs deutlich reduziert. Durch das Verringern der Kavitationszeit wird auch die Kavitationserosion an dem Ventilglied 231 und an den Wänden des Absteuerraums deutlich verringert. Bevorzugt ist das Drosselelement 27 sehr nahe dem Absteuerraum 232 angeordnet, wie dies in Figur 2 dargestellt ist. Je näher das Drosselelement 27 an dem Absteuerraum angeordnet ist, desto wirksamer werden die Geräuschemissionen reduziert. Ferner wird auch so eine dichtende Verbindung zwischen dem Zulaufkanal 21 und einer diesem zugeordneten Kraftstoffzufuhreinrichtung, die üblicherweise mittels eines O-Rings erfolgt, geschont und so deren Lebensdauer erhöht.By the throttle element 27 in particular higher-frequency noise components during the Absteuervorgangs be significantly reduced. By reducing the cavitation time, the cavitation erosion on the valve member 231 and on the walls of the Absteuerraums is significantly reduced. The throttle element 27 is preferably arranged very close to the diversion chamber 232, as shown in FIG. The closer the throttle element 27 is arranged to the diversion chamber, the more effectively the noise emissions are reduced. Furthermore, a sealing connection between the inlet channel 21 and a fuel supply device associated therewith, which usually takes place by means of an O-ring, is also spared and thus increases its service life.

Das Drosselelement wird besonders einfach durch eine Stufenbohrung hergestellt. Dazu erfolgt vorzugsweise zuerst eine Pilotbohrung und die Bohrungen können dann hydroerosiv verrundet werden. Bei dem hydroerosiven Verrunden bewirken in einem Fluid befindliche Partikel das Verrunden der vorgegebenen Bereiche. Das Drosselelement 27 kann jedoch auch als Einsetzteil in den Zulaufkanal 21 eingesetzt sein.The throttle element is particularly easily produced by a stepped bore. For this purpose, preferably first a pilot hole and the holes can then be rounded hydroerosive. In the hydroerosive rounding particles present in a fluid cause the rounding of the given Areas. However, the throttle element 27 may also be used as an insert in the inlet channel 21.

In einer weiteren Ausführungsform der Pumpe-Düse-Vorrichtung (Figur 3) sind mindestens zwei Drosselelemente 60, 61, 62, 63 in dem Zulaufkanal 21 angeordnet. Durch eine geeignete Dimensionierung der Drosselelemente 60 bis 63 und ein geeignetes Beabstanden der Drosselelemente 60 bis 63 können vorgegebene Frequenzen der Druckschwingungen des Kraftstoffs in dem Zulaufkanal 21 gezielt gedämpft werden oder in vorgegebene andere, vorzugsweise für den Menschen nicht hörbare, Frequenzbereiche transformiert werden. Dabei wirken die Drosselelemente 60 bis 63 im Zusammenspiel mit dem Zulaufkanal 21 als Resonatoren und reflektieren jeweils Druckwellen mit einer vorgegebenen Wellenlänge, so dass die entsprechende Welle dissipiert.In a further embodiment of the pump-nozzle device (FIG. 3), at least two throttle elements 60, 61, 62, 63 are arranged in the inlet channel 21. By a suitable dimensioning of the throttle elements 60 to 63 and a suitable spacing of the throttle elements 60 to 63 predetermined frequencies of the pressure oscillations of the fuel in the inlet channel 21 can be specifically damped or transformed into predetermined other, preferably not audible to humans, frequency ranges. In this case, the throttle elements 60 to 63 interact with the inlet channel 21 as resonators and each reflect pressure waves having a predetermined wavelength, so that the corresponding wave dissipates.

Es ist vorteilhaft, wenn das oder die Drosselelemente 27, 60 bis 63 und der Absteuerraum so ausgebildet sind, dass der Pumpraum 13 über den Zulaufkanal 21 auch bei einem vorgegebenen Niederdruckwert, von vorzugsweise 3 bis 10 bar in dem Zulaufkanal 21 innerhalb einer vorgegebenen Zeitdauer befüllbar ist. Die vorgegebene Zeitdauer wird dabei abhängig von der Drehzahl der Kurbelwelle gewählt. Dadurch ist dann gewährleistet, dass der Betrieb der Pumpe-Düse-Vorrichtung, d. h. der frühestmögliche Einspritzbeginn und die maximal mögliche Einspritzmenge durch das/die Drosselelemente 27; 60 bis 63 nicht beeinflusst werden.It is advantageous if the throttle element or elements 27, 60 to 63 and the diversion chamber are designed so that the pump chamber 13 can be filled via the inlet channel 21 even at a predetermined low pressure value, preferably 3 to 10 bar in the inlet channel 21 within a predetermined period of time is. The predetermined time is chosen depending on the speed of the crankshaft. This then ensures that the operation of the pump-nozzle device, d. H. the earliest possible start of injection and the maximum possible injection quantity by the throttle element (s) 27; 60 to 63 are not affected.

Es ist ferner vorteilhaft, wenn der Absteuerraum 232 und das oder die Drosselelemente 27; 60 bis 63 so ausgebildet sind, dass ein Ende des Einspritzens von Fluid über die Düseneinheit mittels des Ventilglieds 231 steuerbar ist und zwar unabhängig von dem oder den Drosselelementen 27; 60 bis 63. Dies hat den Vorteil, dass das Verringern der Geräuschemissionen nicht zu einer Beeinflussung des möglichen Endes des Einspritzens führt. In Figur 4 sind verschiedene Druckverläufe aufgetragen über die Zeit t für verschiedene Ausgestaltungen der Pumpe-Düse-Vorrichtung dargestellt. Der Schwellenwert pthr des Drucks ist der Wert, bei dem die durch den Druck hervorgerufenen Kraft am Nadelabsatz 57 betragsmäßig der Kraft entspricht, die durch das Düsenrückstellmittel 52 hervorgerufen wird. Bei einem Steigen des Drucks wird dann die Düse 56 freigegeben. Bei einem Sinken des Drucks wird die Düse 56 verschlossen durch die Nadel 53.It is also advantageous if the Absteuerraum 232 and the throttle or the elements 27; 60 to 63 are formed so that an end of the injection of fluid through the nozzle unit by means of the valve member 231 is controllable, regardless of the or the throttle elements 27; 60 to 63. This has the advantage that reducing the noise emissions does not affect the possible end of the injection. In Figure 4 are different pressure gradients plotted against time t for various configurations of the pump-nozzle device. Threshold pthr of pressure is the value at which the pressure-induced force on needle hub 57 is the same as the force caused by nozzle return means 52. As the pressure increases, the nozzle 56 is released. When the pressure drops, the nozzle 56 is closed by the needle 53.

Die durchgezogene Linie in Figur 4 zeigt einen beispielhaften Druckverlauf bei einer Pumpe-Düse-Vorrichtung gemäß Figur 2 in dem Ablaufkanal 22. Zu einem Zeitpunkt t1 wird der Schwellenwert pthr des Drucks überschritten und somit beginnt die Kraftstoffzumessung in den Zylinder, wie dies in Figur 5 anhand der zugemessenen Kraftstoffmenge Qinj aufgetragen über die Zeit t dargestellt ist. Zu einem Zeitpunkt t4 wird dann der Schwellenwert pthr des Drucks wieder unterschritten und somit die Kraftstoffzumessung beendet.The solid line in Figure 4 shows an exemplary pressure curve in a pump-nozzle device according to Figure 2 in the drain passage 22. At a time t1, the threshold value pthr of the pressure is exceeded and thus the fuel metering begins in the cylinder, as in Figure 5 is plotted over the time t, based on the metered amount of fuel Qinj. At a time t4, the threshold value pthr of the pressure is then fallen below again and thus the fuel metering is ended.

Das Drosselelement 27 ist so ausgebildet und angeordnet und ebenfalls der Absteuerraum 27 ist so ausgebildet, dass im Vergleich zu einer Pumpe-Düse-Vorrichtung ohne das Drosselelement 27 der Druckabfall bei Drücken oberhalb des Schwellenwerts pthr identisch ist (siehe gestrichelten Verlauf des Drucks).The throttle element 27 is formed and arranged, and also the Absteuerraum 27 is formed so that compared to a pump-nozzle device without the throttle element 27, the pressure drop at pressures above the threshold value p thr is identical (see dashed line of pressure).

Punktiert ist der Druckverlauf für den Fall dargestellt, bei dem das Drosselelement 27 so dimensioniert ist, dass bei dem vorgegebenen Niederdruckwert kein vollständiges Befüllen des Pumpraums 13 gewährleistet ist. In diesem Fall findet der Druckaufbau in dem Pumpraum 13 nur verzögert statt und der Schwellenwert pthr wird erst zum Zeitpunkt t2 erreicht. Das Drosselelement 27 ist in diesem Fall so dimensioniert, dass nach einem Absteuern des Ventils durch die Drosselwirkung des Drosselelements 27 der Druck bereits oberhalb des Schwellenwerts pthr langsamer abfällt als im ungedrosselten Fall. Dies hat zusätzlich zur Folge, dass auch das Ende der Kraftstoffzumessung erst verzögert im Zeitpunkt t5 auftritt.Dotted the pressure curve is shown for the case in which the throttle element 27 is dimensioned so that at the predetermined low pressure value no complete filling of the pump chamber 13 is ensured. In this case, the pressure build-up in the pump chamber 13 takes place only delayed and the threshold value pthr is reached only at the time t2. The throttle element 27 is dimensioned in this case so that after a Absteuern of the valve by the throttle effect of the throttle element 27, the pressure already above the threshold value p thr slower than in the unthrottled case. This In addition to the consequence that also the end of the fuel metering occurs only delayed at time t5.

Die strichpunktierte Linie setzt den Verlauf der punktierten Linie für den Fall fort, dass das Drosselelement 27 so dimensioniert ist, dass seine Drosselwirkung erst unterhalb des Schwellenwerts pthr zu einer Veränderung des Druckabfalls im Vergleich zum ungedrosselten Fall führt.The dot-dashed line continues the course of the dotted line in the event that the throttle element 27 is dimensioned so that its throttling action leads to a change in the pressure drop only below the threshold value p thr compared to the unthrottled case.

Claims (7)

  1. Unit injector with a pump and a valve with a valve element (231) which controls the hydraulic coupling of a cut-off control chamber (232) with an outlet channel (22), which is hydraulically coupled to the pump and an injection unit (5), with an inlet channel (21) being provided which is routed from a low-pressure side connection of the unit injector through to the valve, which is hydraulically coupled to the cut-off control chamber (232), characterized in that
    the inlet channel (21) to the valve element (231) includes a throttle element (27; 60 to 63).
  2. Unit injector in accordance with claim 1, characterized in that the throttle element (27; 60 to 63) is arranged close to the cut-off control chamber (232).
  3. Unit injector in accordance with one of the previous claims, characterized in that, the cut-off control chamber (232) and the throttle element (27; 60 to 63) are embodied so that the pump is able to be filled completely with fluid via the inlet channel (21) even at a predetermined low-pressure value in the inlet channel (21) within a predetermined period.
  4. Unit injector in accordance with one of the previous claims, characterized in that, the cut-off control chamber (232) and the throttle element (27; 60 to 63) are embodied so an end of the injection of fluid via the injection unit (5) can be controlled by means of the valve element (231), independently of the throttle element (27; 60 to 63).
  5. Unit injector in accordance with one of the previous claims, characterized in that the throttle element (27; 60 to 63) is embodied in the form of a stepped hole of the inlet channel (21).
  6. Unit injector in accordance with one of the previous claims, characterized in that at least two throttle elements (60 to 63) are arranged in the inlet channel (21).
  7. Unit injector in accordance with claim 6, characterized in that the throttle elements (60 to 63) are arranged spaced from one another so that they damp out predetermined frequencies of the pressure fluctuations of the fluid in the inlet channel (21) or transform them into predetermined other frequency ranges.
EP04017275A 2003-07-24 2004-07-22 Unit injector Not-in-force EP1503073B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2003133787 DE10333787A1 (en) 2003-07-24 2003-07-24 Pump-nozzle apparatus
DE10333787 2003-07-24

Publications (2)

Publication Number Publication Date
EP1503073A1 EP1503073A1 (en) 2005-02-02
EP1503073B1 true EP1503073B1 (en) 2007-09-05

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Application Number Title Priority Date Filing Date
EP04017275A Not-in-force EP1503073B1 (en) 2003-07-24 2004-07-22 Unit injector

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EP (1) EP1503073B1 (en)
DE (2) DE10333787A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010001170A1 (en) 2010-01-25 2011-07-28 Robert Bosch GmbH, 70469 Injection device with reduced pressure oscillations

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Publication number Priority date Publication date Assignee Title
GB9616521D0 (en) * 1996-08-06 1996-09-25 Lucas Ind Plc Injector
GB9720003D0 (en) * 1997-09-20 1997-11-19 Lucas Ind Plc Drive circuit
DE19835494C2 (en) * 1998-08-06 2000-06-21 Bosch Gmbh Robert Pump-nozzle unit
DE10023960A1 (en) * 2000-05-16 2001-11-22 Bosch Gmbh Robert Fuel injection device for internal combustion engine has choke gap formed between choke section upstream of valve seat in bore and casing surface
DE10123914B4 (en) * 2001-05-17 2005-10-20 Bosch Gmbh Robert Fuel injection device with pressure booster device and pressure booster device

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Title
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Publication number Publication date
DE502004004853D1 (en) 2007-10-18
EP1503073A1 (en) 2005-02-02
DE10333787A1 (en) 2005-02-24

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